RFR: 7062: Update to the Eclipse 2020-12 platform

[Jie Kang]

On Fri, 18 Dec 2020 13:25:39 GMT, Marcus Hirt <hirt at openjdk.org> wrote:

>> From a testing perspective, I opened https://bugs.openjdk.java.net/browse/JMC-7068 today, where `JfrRecordingTest` hangs on Fedora after the 2020-09 update, and it continues with this 2020-12 patch.
>> 
>> On the first run of uitests I only ran `JfrRecordingTest` to see if it'd hang, and it did.
>> 
>> The second time I ran the uitests I had a test failure in [console.ui.FreezeTableTest](https://github.com/openjdk/jmc/blob/62ed0e874081870d262e41fa375b16e888329b75/application/uitests/org.openjdk.jmc.console.uitest/src/test/java/org/openjdk/jmc/console/uitest/FreezeTableTest.java#L82):
>> Errors: 
>>   FreezeTableTest.freeze:82 » IndexOutOfBounds Index 0 out of bounds for length ...
>> 
>> On the third run, it SIGSEGV'd at `org.openjdk.jmc.flightrecorder.uitest.ControlRecordingsTest`.
>> 
>> On the fourth run I ran only the tests under `flightrecorder.uitest` (without `JfrRecordingTest`), and made it through okay. 
>> 
>> From a review perspective, I'm not sure how to review this one. Dependency freeze (if I'm recalling correctly) was supposed to be on pace with rampdown 1 on November 23rd, so I might have to defer to @jiekang for more insight this one, but the eclipse fedora rpm repo was recently updated to 2020-09 (4.17.0).. so I'm not sure if an extra update 2020-12 will impact a hopeful jmc release timeline on our side.
>
> Oracle has already stated that they are considering releasing on 2020-06 (@guruhb - is this still the case?). Even if we take it (it does contain Big Sur-related fixes), vendors can decide which version they want to build and release on (i.e. -P<platform> when packaging).

Yes, as downstream we can select a different release if need be; well it isn't necessarily in our hands with Fedora but anyways.

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PR: https://git.openjdk.java.net/jmc/pull/185